From the App Store: Create professional sounding music in just minutes. Or perhaps you just want to lay down a percussion track and play keyboards over the top, you can do that too.
Online manual: http://www.image-line.com/support/GMMobileHelp/
About Groove Machine Mobile
Synthesizer: Load from the extensive library of bass, keys, lead, pad, sfx and synth sounds. The flexible dual-oscillator, wave-shape driven, design with filters, 3 envelopes and LFO architecture will ensure you can create fresh and unique sounds for years to come. Listen to the presets and you will know how powerful the Groove Machine Mobiles synths are.
Sample Player: Choose from over 20 multi-sampled instruments covering Piano, strings, organ, bass, guitar, flute, harp and more.
Drums & percussion: Punch out a beat on the 10 drum pads. The velocity-through-position feature will allow you to play with feeling to get the right groove. Layer two samples per-pad for complex sample mash-ups. A comprehensive library of percussion samples is included covering kicks, snares, toms, hats, cymbals, sfx and more.
Keyboards: Take control over the synthesizers with Groove Machine Mobiles two-tier touch keyboard, perfect for playing chords and melodies. The visual feedback will even help you to learn to play music just by watching the existing projects play.
Effects: A wide array of modern and classic effects are available including a Bit Crusher (for lo-fi gritty sounds), Flanger & Phaser (to create complex stereo washes and spacey effects), Filters (low, high pass & vowel-voice simulation), Delay (echoes), Reverb (to simulate the sound of large halls through to tight spaces), Panning (so you can spread your sounds across your speakers) and Ring modulation (creating screaming-feedback type sounds).
Sequencing: After recording a performance Groove Machine Mobile’s touch-optimized easy editing features make it a breeze. You can edit in all the musical parts from scratch here too. The Piano-roll allows note entry and step-entry for percussion tracks. Finally, record and edit the movement of almost any knob or control with the Automation editor.